1. Field of the Invention
The present invention relates to decomposable products and their fabrication method and, more specifically, to a method of fabricating products that are decomposable to microbes.
2. Description of the Related Art
The so-called xe2x80x9cwash-freexe2x80x9d kitchen utensils are commonly molded from polystyrene polymers or made of hard paper material or wooden slats. Disposable kitchen utensils molded from polystyrene polymers are not decomposable to microbes. Using paper or wooden material to make disposable kitchen utensils need to fell a big amount of trees.
In recent years, manufacturers have created a variety of substitutes for making disposable kitchen utensil causing damage to the environment. These substitutes are commonly obtained from plant fibers (shells of wheat or rice), and molded into the desired finished products (bowls, dishes, pots, etc.) by a compression-molding machine. A disposable product made according to this method is decomposable to microbes. However, this method still has drawbacks including low structural strength and poor waterproof effect of finished products, complicated procedure, high manufacturing cost, etc.
Japanese patent publication No. 2000-355008 (P2000-355008A) discloses a method of fabricating decomposable products, in which plant material powder, mainly obtained from rice shells, is mixed with a decomposable substance containing a bonding agent into a mixture, and then the mixture is molded into a green ware at a predetermined pressure and temperature, and then woven fabric or non-woven fabric material is arranged on the green ware so as to obtain a semi-finished product, and then the semi-finished product is molded into the desired finished product at a predetermined pressure and temperature. Alternatively, prepared materials are mixed into a paste-like mixture and then applied to woven fabric or non-woven fabric materials, and then the mixture-coated woven fabric or non-woven fabric materials are dried into slats, and then prepared paste-like mixture is applied to the slats again, and at final the slated materials are molded into the finished products at a predetermined pressure and temperature. The use of woven fabric or non-woven fabric materials is to reinforce the strength of plant powder material. This method is complicated, resulting in high manufacturing cost of the finished products.
Decomposable products made according to the known decomposable product fabrication methods are still not acceptable to the market in practical use (strength, waterproof property, thermal stability, etc.), environmental protection (highly decomposable to microbes), and manufacturing cost. In order to reinforce the structural strength of the finished product, resin content may be relatively increased, for example, China Patent No. 97107979 teaches the use of 5xcx9c20% thermal melting glue; China Patent No. 98121944 teaches the use of 10xcx9c35% urea-formaldehyde resin. However, because resin is not decomposable to microbes, the finished product does not meet the requirement for environment protection. Adding water soluble resin or starch to plant powder material can make a product decomposable to microbes, however a product made according to this method has poor waterproof, oil resistant, acid-proof, and alcohol resistant properties and low thermal stability power.
The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a decomposable product fabrication method, which is simple and economic to perform. It is another object of the present invention to provide a decomposable product fabrication method, which does not cause any environmental problem. It is still another object of the present invention to provide a decomposable product, which provides satisfactory waterproof, oil resistant, acid-proof, and alcohol resistant properties as well as high thermal stability power. The decomposable product fabrication method includes the steps of a) preparing a plant powder obtained by crushing plant fibers and a viscous fluid additive containing a bonding agent, (b) mixing the prepared materials into a viscous mixture, c) drying said viscous mixture by baking, so as to obtain a prepared raw material having a moisture content below a predetermined value, d) using a compression-molding machine to mold said prepared raw material into a green ware under a predetermined molding temperature and molding pressure, and discharging steamy air out of the mold during compression molding, e) covering said green ware with a layer of waterproof coating, so as to obtain a semi-finished product, and f) baking said semi-finished product to a dry status, so as to obtain a finished product, and then cooling the finished product thus obtained.